Patent Application
20230170119
The disclosure pertains generally to superconducting magnets, and more particularly to stacking of plates, that contain wound superconductors, according to desired Lorentz loading.
Superconducting magnets with non-insulated (NI) high temperature superconductor (HTS) windings have demonstrated the ability to enhance superconducting magnet performance in three key metrics: overall current density, thermal stability, and mechanical integrity. A spiral-grooved, stacked-plate, non-insulated superconducting magnet design was conceived to fully exploit these characteristics in a design that is both commercially viable and scalable to large bore magnets—pushing system performance to handle the highest magnetic fields and stored magnetic energies possible. This design utilizes a structurally robust spiral-grooved baseplate as the basic building block. Grooves are loaded with a composite of HTS tapes and co-wind materials in a variety of configurations. These are assembled into single or double pancake modules, which are stacked together to form the winding pack for a high field magnet. Further details of this design may be found in U.S. application Ser. No. 16/233,410, filed Dec. 27, 2018 and entitled “Spiral-Grooved, Stacked-Plate Superconducting Magnets And Related Construction Techniques,” the entire contents of which are incorporated herein by reference.
Disclosed embodiments include magnet plates stacked in a pattern that is a function of the expected operational field strength at different positions in the stack, thereby ensuring that the resulting loads always are directed into the grooves, and thus onto the structural plate itself. This is accomplished by altering the baseplate orientations, e.g. by ‘flipping’ the geometry of the plates such that the conductor placement in the lower half of the stack ‘mirrors’ that of the upper half, and applying suitable modifications to the mechanical fasteners and electrical joints. A winding pack with this design provides several advantages, at least: greater flexibility in the choice of materials used to secure the conductor in its groove, reduced structural requirements of those materials, greater manufacturing tolerances, increased inherent tolerance to construction flaws, or a combination thereof.
Thus, a first embodiment is a system comprising a plurality of magnet plates. Each of the magnet plates has a flat surface opposite a grooved surface. Each of the magnet plates also has a conductor that passes through grooves in the grooved surface. The plurality of magnet plates are arranged in a stack so that, when a current is applied to the conductor of each of the magnet plates to generate a magnetic field, a Lorentz force resulting from the generated magnetic field presses each conductor into its respective grooves.
In some embodiments, one half of the magnet plates have grooved surfaces arranged toward a top of the stack, and the other half of the magnet plates have grooved surfaces arranged toward a bottom of the stack. Some embodiments further have a second plurality of magnet plates, each of the second plurality of magnet plates having a flat surface and a grooved surface, each of the second plurality of magnet plates having a conductor that passes through grooves in the grooved surface. In these embodiments, one half of the second plurality of magnet plates have grooved surfaces arranged toward a left of the stack, and the other half of the magnet plates have grooved surfaces arranged toward a right of the stack. Thus, the second plurality of magnet plates have an orientation that is perpendicular to an orientation of the first plurality of magnet plates.
In some embodiments, greater than one half of the magnet plates have grooved surfaces arranged toward a top of the stack, and the remaining fewer than one half of the magnet plates have grooved surfaces arranged toward a bottom of the stack.
In some embodiments, at least one of the magnet plates has a conductor that comprises a homogeneous rare-earth copper oxide superconductor.
In some embodiments, at least one of the magnet plates has a conductor that comprises a stack of high temperature superconductor (HTS) tape. The conductor may have a circular cross-section, or a square cross-section, or another shape of cross-section.
In some embodiments, at least one of the magnet plates has a conductor that comprises a plurality of stacks of high temperature superconductor (HTS) tape. The plurality of stacks of HTS tape may be arranged around a cooling channel for removing heat generated by the plurality of stacks of HTS tape.
In some embodiments, at least one of the magnet plates has a conductor that is soldered into the grooves in the grooved surface, or is potted into the grooves in the grooved surface using an epoxy.
In some embodiments, at least one of the magnet plates comprises a steel or a glass-fiber composite.
Another embodiment is a housing having grooved surfaces, the housing having a plurality of conductors that each pass through a groove in one of the grooved surfaces. When a current is applied to each of the plurality of conductors to generate a magnetic field, a Lorentz force resulting from the generated magnetic field presses each conductor into its respective groove.
In some embodiments, at least one of the plurality of conductors comprises a homogeneous rare-earth copper oxide superconductor.
In some embodiments, at least one of the plurality of conductors comprises a stack of high temperature superconductor (HTS) tape. The conductor may have a circular cross-section, or a square cross-section, or another shape of cross-section.
In some embodiments, at least one of the plurality of conductors comprises a plurality of stacks of high temperature superconductor (HTS) tape. The plurality of stacks of HTS tape may be arranged around a cooling channel for removing heat generated by the plurality of stacks of HTS tape.
In some embodiments, at least one of the plurality of conductors is soldered into its groove, or is potted into its groove using an epoxy.
In some embodiments, the housing comprises a steel or a glass-fiber composite.
Yet another embodiment is a magnet system comprising a plurality of magnet winding packs. Each winding pack has a plurality of magnet plates. Each of the magnet plates has a flat surface opposite a grooved surface, and a conductor that passes through grooves in the grooved surface. The plurality of magnet plates are arranged in each winding pack so that, when a current is applied to the conductor of each of the magnet plates to generate a magnetic field, a Lorentz force resulting from the generated magnetic field presses each conductor into its respective grooves.
In some embodiments, at least two of the magnet winding packs have different arrangements of magnet plates. The magnet system may be arranged as a solenoid, or arranged as a toroid.
A further embodiment is a magnet comprising a plurality of plates, each of the plates having a flat surface opposite a grooved surface, each of the plates comprising a conductor that passes through grooves in the grooved surface. The plurality of plates includes a first plate and a second plate arranged such that the flat surface of the first plate and the flat surface of the second plate both lie between the grooved surface of the first plate and the grooved surface of the second plate.
In some embodiments, the flat surface of the first plate contacts the flat surface of the second plate.
In some embodiments, the flat surface of the first plate and the flat surface of the second plate contact opposing sides of a layer of insulation.
In some embodiments, at least one of the plates comprises a conductor having a stack of high temperature superconductor tapes. The conductor may have a circular cross-section or a square cross-section.
It is appreciated that the concepts, techniques, and structures disclosed herein may be embodied in other ways, and that the listing of certain embodiments above does not limit the inventive scope of this disclosure.
The manner and process of making and using the disclosed embodiments may be appreciated by reference to the figure of the accompanying drawings. It should be appreciated that the components and structures illustrated in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principals of the concepts described herein. Like reference numerals designate corresponding parts throughout the different views. Furthermore, embodiments are illustrated by way of example and not limitation in the figures, in which:
Large magnetic self-fields develop in the winding packs of superconducting magnets during operation. Consequently, large Lorentz loads develop on the conductors. For winding packs that consist of a series of stacked plates, each with conductors embedded into grooves within the plate, the component of Lorentz load that is aligned normal to the plane of the plates, the so-called out-of-plane Lorentz load, plays an important role. Consider a winding pack that is constructed by stacking the plates with all the grooves facing in the same direction. In half of these conductors, as known in prior art winding packs, the loads are directed into their respective grooves, while for the other half of these conductors, the loads are directed out of their respective grooves. Thus, conductors in the latter half experience loads that are not borne by the structural material of the baseplate, but instead by non-structural elements, such as copper caps, solder, or coolant channels.
Disclosed embodiments exploit a fundamental principle of physics; namely that conductors (such as those in a magnet winding pack, for example) having current flowing in parallel to each other are attracted due to the self-magnetic fields. To apply this principle, magnet plates in a stack of magnet plates are oriented so that, under operating self-field, the conductors of each plate pull themselves in a direction which aids the structural integrity of the stack of plates. That is, in accordance with the concepts described herein, it has been recognized that it is possible to arrange (or orient) plates such that forces resultant from current flowing through the conductors disposed in grooves of the plates occur in a desired direction. For example, in embodiments comprising a stack of plates having high temperature superconductors (e.g. an HTS cable or one or more HTS tapes) disposed in grooves thereof, the plates may be oriented such that forces on the HTS push the HTS into the grooves of the plate. That is, the HTS tapes are pulled into (rather than out of) the grooves of the plate.
Referring now to
A “mirrored” winding pack is one in which the conductor groove geometry is ‘mirrored’ about a central symmetry plane. The spiral-grooved, stacked plate magnet design of
It is recognized that any even number of magnet plates may be mirrored across a central symmetry plane when a symmetric magnetic field is present, and thus that the fact that six magnet plates are shown in
This design has certain derivative benefits. For example, in magnet designs having coolant channels between the magnet plates, such channels located at the reflection plane can be reduced significantly in cross-sectional area or eliminated, as desired.
Thus, the embodiment of
It is appreciated that, in some embodiments, each conductor 14 may be either soldered into its groove, or potted using an epoxy. The magnet plates 10a-10c, 12a-12c each may be an electrical conductor, such as steel, but may be an insulator such as a glass-fiber composite.
As will become apparent from the description below, it is recognized that the broad concepts described herein may be applied to many different types of plates, grooves, and cables. The plates, grooves, and cables may be provided having a wide variety of shapes, and several such shapes are illustrated in the Figures herein. Any type of superconducting cable may be disposed in a groove having a cross-sectional shape. In some embodiments, cables (e.g. cables 14) may comprise an HTS tape stack. In some embodiments, cables (e.g. cables 14) may comprise a former having one or more grooves therein into which superconducting material (e.g. HTS tape) may be disposed. Also, cables (e.g. cables 14) may be provided having any regular or irregular cross-sectional shape including, but not limited to round, oval, square or rectangular. Similarly, grooves (e.g. groove 16) may be provided having any regular or irregular cross-sectional shape including, but not limited to round, oval, square or rectangular.
Referring now to
The embodiment of
For applications in which the magnet experiences an external field component that is parallel to the plates, the net out-of-plane I×B loads will be shifted about the mirror reflection plane. This situation may be encountered, for example, in a toroidal field (TF) winding pack for a tokamak. In this situation, the TF winding pack will be exposed to magnetic fields generated by the poloidal field (PF) coil set. Because the TF magnet self-fields are much stronger than the PF magnet fields at the location of the TF conductors, the shift in the out-of-plane I×B load pattern is small, but varies according to the position of the plate within the stack.
In this connection, in
It is recognized that any number of magnet plates may be asymmetrically mirrored across a symmetry plane (e.g. plane 32), and thus that the fact that six magnet plates are shown in
In contrast to the magnetic self-field generated by the conductors in
Thus,
It is appreciated that embodiments of the concepts, techniques, and structures disclosed herein are not dependent on the conductor configuration. Thus, in some embodiments the conductor includes a high temperature superconductor (HTS) made of a homogeneous rare-earth copper oxide (e.g. REBCO), as shown in
Thus, in
The cross section of
In more detail, the local fields in the topmost winding pack 90a during operation are generally toward the center of the pack, with a slight bias toward the center of the solenoid. Three of the magnet plates 94a-94c in the topmost winding pack 90a have grooves in their top surfaces, and the fourth magnet plate 94d has grooves in its bottom surface. This arrangement balances the self-field of this winding pack with the fields generated by the other winding packs so that all conductors are pulled into their grooves. Using the same principles, the bottommost winding pack 90c is the mirror image of the topmost winding pack 90a. Thus, its innermost magnet plate 98a has grooves in its top surface, while the three outermost magnet plates 98b-98d have grooves in their bottom surfaces.
The self-field in the middle winding pack 90b and the sum of the fields generated by the other winding packs both generate Lorentz forces toward the center of the solenoid during operation. The middle winding pack 90b balances the magnetic fields differently than the topmost and bottommost winding packs. Thus, the middle winding pack 90b is purely symmetric about a central symmetry plane 92b. In particular, magnet plates 96a and 96b have grooves in their top surfaces, while magnet plates 96c and 96d have grooves in their bottom surfaces in a perfectly mirrored configuration.
Thus,
It is appreciated that in embodiments, the number of magnet plates in the various winding packs, and their particular stacking arrangements, may be determined by the operational requirements of the application to which the concepts, techniques, and structures disclosed herein are applied. The particular numbers of plates shown in each stack or winding pack in each of the Figures herein does not necessarily limit the scope of the inventive subject matter.
Persons having ordinary skill in the art may appreciate other embodiments of the concepts, results, and techniques disclosed herein. It is appreciated that superconducting cables and magnet plates configured according to the concepts and techniques described herein may be useful for a wide variety of applications, including applications in which the superconducting cable is wound into a coil to form a magnet. For instance, one such application is conducting nuclear magnetic resonance (NMR) research into, for example, solid state physics, physiology, or proteins, for which such cables may be wound into a magnet. Another application is performing clinical magnetic resonance imaging (MRI) for medical scanning of an organism or a portion thereof, for which compact, high-field magnets are needed. Yet another application is high-field MM, for which large bore solenoids are required. Still another application is for performing magnetic research in physics, chemistry, and materials science. Further applications is in magnets for particle accelerators for materials processing or interrogation; electrical power generators; medical accelerators for proton therapy, radiation therapy, and radiation generation generally; superconducting energy storage; magnetohydrodynamic (MHD) electrical generators; and material separation, such as mining, semiconductor fabrication, and recycling. It is appreciated that the above list of applications is not exhaustive, and there are further applications to which the concepts, processes, and techniques disclosed herein may be put without deviating from their scope.
As used herein, a “high temperature superconductor” or “HTS” refers to a material that has a critical temperature above 30 K, wherein the critical temperature refers to the temperature below which the electrical resistivity of the material drops to zero.
Illustrative examples of arranging magnet plates and conductors within grooves are described herein and illustrated in the drawings. It will be appreciated that the particular size and shape of these grooves are provided merely as examples and that no particular cross-sectional shape or size is implied as being necessary or desirable unless otherwise noted.
Having thus described several aspects of at least one embodiment which illustrate the described concepts, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the concepts described herein. Further, though advantages of the concepts described herein are indicated, it should be appreciated that not every embodiment of the technology described herein will include every described advantage. Some embodiments may not implement any features described as advantageous herein and in some instances one or more of the described features may be implemented to achieve further embodiments. Accordingly, the foregoing description and drawings are by way of example only.
Various aspects of the concepts described herein may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments.
Also, the concepts described herein may be embodied as a method. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.
Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.
The terms “approximately” and “about” may be used to mean within ±20% of a target value in some embodiments, within ±10% of a target value in some embodiments, within ±5% of a target value in some embodiments, and yet within ±2% of a target value in some embodiments. The terms “approximately” and “about” may include the target value. The term “substantially equal” may be used to refer to values that are within ±20% of one another in some embodiments, within ±10% of one another in some embodiments, within ±5% of one another in some embodiments, and yet within ±2% of one another in some embodiments.
The term “substantially” may be used to refer to values that are within ±20% of a comparative measure in some embodiments, within ±10% in some embodiments, within ±5% in some embodiments, and yet within ±2% in some embodiments. For example, a first direction that is “substantially” perpendicular to a second direction may refer to a first direction that is within ±20% of making a 90° angle with the second direction in some embodiments, within ±10% of making a 90° angle with the second direction in some embodiments, within ±5% of making a 90° angle with the second direction in some embodiments, and yet within ±2% of making a 90° angle with the second direction in some embodiments.
Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
For purposes of the description above, the terms “upper,” “lower,” “right,” “left,” “vertical,” “horizontal, “top,” “bottom,” and derivatives thereof” shall relate to the described structures and methods, as oriented in the drawing figures. The terms “overlying,” “atop,” “on top,” “positioned on” or “positioned atop” mean that a first element, such as a first structure, is present on a second element, such as a second structure, where intervening elements such as an interface structure can be present between the first element and the second element. The term “direct contact” means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediary layers or structures at the interface of the two elements.
In the foregoing detailed description, various features of embodiments are grouped together in one or more individual embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claims require more features than are expressly recited therein. Rather, inventive aspects may lie in less than all features of each disclosed embodiment.
Having described implementations which serve to illustrate various concepts, structures, and techniques which are the subject of this disclosure, it will now become apparent to those of ordinary skill in the art that other implementations incorporating these concepts, structures, and techniques may be used. Accordingly, it is submitted that that scope of the patent should not be limited to the described implementations but rather should be limited only by the spirit and scope of the following claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/018962 | 2/22/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63027538 | May 2020 | US |
